Geometric scribing machine



June 17,1930. AIDNFIS'HER 1,763,885

'GEOMETRIC SCRIBING MACHINE 1 Filed Jan. 9, 1928 INVENTIJH.

Patented June 17, 1930 UNITED STATES rA ENr orrlcn ALEXANDER D. FISHER, OF TORONTO, ONTARIO, CANADA, ASSIGNOR TO THE DESIGN-O-GRAPH LIMITED OF TORONTO, CANADA GEOMETRIC' SCRIBING MACHINE Application filed January 9, 1928. Serial No. 245,407.

This invention relates to devices for scribing curves, and my object is to devise apparatus of this nature particularly adapted for use as a toy and which will produce a great variety of patterns by the repetition of curves.

I attain my object by means of the construction which may be briefly described as follows: A rotary table is provided adapted U to carry sheets of paper on which the curves are to be scribed. A crank disk is geared to the table, and has one end of a bar eccentrically connected therewith. This bar is slidably and rockably supported on a fulcrum spaced from the centre of the table and cara ries a scribing point adapted to engage the upper surface of the table or of a sheet of paper secured thereon. Various adJustments are provided whereby the patterns produced are varied at will by the user.

The invention is illustrated in the accompanying drawings in which Fig. 1 is a plan view, partly broken away, of an instrument constructed in accordance with my invention;

Fig. 2 a side elevation of the same; and

Fig. 3 a side elevation of part of the same showing certain of the parts in different positions.

In the drawings like numerals of reference indicate corresponding parts in the different figures.

1 is a base on which the table 2 is mounted to rotate. This table is provided with clamp- 5 ing screws 3, by means of which sheets of paper may be secured to the upper surface of the table. An arm 4 is mounted on the base to swing concentric with the table. The fulcrum post 5 is carried at the outerend of this arm, the post being rotatable on a vertical axis. This post is provided with a notch 6 adapted to slidably receive the bar 7. The other end of this bar is adapted for pivotal engagement with the crank disk 8, which is mounted to rotate on a vertical axis at the outer end of an arm 9 connected with the series of holes 10 formed in the upper sur- U face of the disk 8. Any desired throw with in the limits of adjustment may be thus imparted to the end of the bar 7 when the crank disk is rotated. A crank handle 11 is pro vided, by means of which the disk may be rotated. l

The crank disk and table require to be simultaneously rotated. For this purpose 1 show the rotary table as driven from the crank disk by means of the rotary idler 12 mounted, as hereinafter described, and preferably adapted to engage in the grooves 13, 14 formed in the rim of the table and crank disk, as shown. It is preferable that the rate of movement of the table relative to the ing the position of the idler the rate of drive may be varied as desired. The grooves thus form grooved stepped pulleys any complementary pair of which may be connected by the idler.

While any suitable device may be employed to carry the idler and shift its position, I show a simple and effective construction for this purpose. The idler 12 is journalled at one end of an arm 15. The arm is formed with a longitudinal slot 16, so that it is longitudinally'slidable on a headed pin 17 connected with the arm 9. A bent spring 18 is secured at one end to the arm 9 and at its other end engages behind the downwardly bent end 19'of the arm 15. The spring thus tends to draw the idler into close contact with the pair of grooves with which it may be engaged. At the same time, by pressing on the end of the arm 15 the idler may be disengaged. It is then free to be moved up or down on the pivot on which it is mounted. After it has been moved to a fresh position, the spring 18 will re-engage it with the grooves in the table and crank disk opposite which it has been positioned. v

The bar 7 is adapted to carry a scribing pointfor co-operation with a sheet of paper securedto the rotary table. This scribing point is preferably so carried that its position longitudinally of the bar may be var ed,

and also its distance from the bar. I show for this purpose a slide 21 adapted to both slide and rock on'the bar. A spring dog 22 is secured to the slide and is adapted to engage. in any one of the series of circumferential grooves 23 formed on the bar 7.. An arm 24 extends from theslide and is providedat its outer end with aclamp 25, by means of which a pen'or pencil 26 may be securedto the arm to serve as a scribing point. An arm 27 extends out from the slide 21 and is provided with a removable weight 28. The weigh-tis used to give the necessary pressure when a pencil is'bei'ng used as the scribing point. If a fountain pen is used, the weight is unnecessary and may be removed.

It is apparent from the above description that the scribing point is readily adjustable longitudinally ofthe bar, while its distance from the, bar may be varied by varying the extent of its projection from the clamp 25.

, peated to form a pattern; the precise nature of which depends on the adjustments that have been made. For example-,the point of connection'of the bar with the crank disk may be varied; the position of the scribing point longitudinally of the bar 7 may be varied; the distance of the scribing point from the bar 7 may be Varied; the relative position of the fulcrum 5 and axes of the rotary table and crank disk may be varied; and finally, the relative speed of rotation of the crank disk and rotary table may be varied.

' It is'desira-ble; if'possible, to keep a record ofthe various adjustments in order that any pattern produced may be repeated whenever desired. This'may be done by keeping a record of'the particular hole 10 in the crank disk with which the bar 7 is connected; by keeping a record of the particular groove 23 in the bar 7 with which the dog 22 is engaged; by'keeping a record of the position of the arm 4 and bykeeping a record of the extension of the scribing point from the clamp.

Special provision is desirable to facilitate keeping record of the last two adjustments.

I therefore provide the post 1 with a scale 29, with which co-operates an index finger 30 conn'ected with the arm a.

To determine the position of the scribing point I provide a gauge rod 31 suitable scaled, as shown which slides through a hole in the arm 24,'and which maybe clamped therein by means of the set screw 32. After a pattern has been scribed, the gauge rod may be slipped into place and its position noted. Then it is desired to again set the scribing point in the same position, the gauge rod is passed through the arm until it is in the original position as indicated by the scale.

It-is then clamped in place and the arm lowered until the end of the gauge contacts with the table. If the scribing point be'now inserted in place and position with its point in engagement with the table, it will then occupy the original position and may be clamped in place.

What I claim as my inventionis: I 1. A geo'metricscribing machine comprising a rotary table; a crank disk; a bar substanjtially parallel to the surface of the table having a pivotal connection with the disk eccentric thereto; a fulcrum spaced from the centre of the table s'lida'bly and rockably sup porting the said bar; a scribing point carried by the said bar adapted to engage the upper surface of thetable; and a variable speed drive between the table and crank disk comprising stepped friction pulleys connected with the table and with the crank disk,' and an idler friction disk adj ustably mounted for engagement with any two complementary friction pulleys. 4 i

2. A geometric scribing machine compris-' ing a rotary table; a crank-disk; a bar substantially parallel to the surface of the table having a pivotal connection with the diskv eccentri'cthereto; a fulcrum spaced from the centre of the table slidably and rockabl-y supporting the said bar; a scribing point carried by the said bar adapted to engage the upper surface of said table; and-a variable speed 1 drive between the table and crank disk comprising stepped friction pulleys connected with the table and with the crank disk, an idler friction disk; an arm adjustablelongitudinally of itself on a stationary part of the apparatus; a pivot carried by said arm paral* lel to the axes of the pull'eys'on whichpivot the idler is slidable to bring it into position for engagement with any two complementary pulleys.

3. A geometric scribing machine comprising a rotary table; a crank disk; at bar substantially parallel to'the surface of the table having a pivotal connection with the disk eccentric thereto; -a fulcrum spaced from the centre of the table'slidably and rockably supporting the said bar; a scribing point carried by the said bar adapted to engage the upper surface of the table; and a drive connection between the table and crank disk comprising an idler directly geared to the crank disk and the table whereby the table rotates in the same direction as the crank disk.

4. A geometric scribing machine comprising a rotary table; a crank disk geared to the table; a bar substantially parallel to the surface of the table having a pivotal connection with the disk eccentric thereto; a fulcrum spaced from the centre of the table slidably and rockably supporting the said bar; a scribing point carried by the said bar adapted to engage the upper surface of the table; an arm pivoted concentric with the table and carrying the fulcrum aforesaid at its outer end, whereby the relative positions of the centers of the table, crank disk, and fulcrum may be varied in a horizontal plane.

5. A geometric scribing machine comprising a rotary table; a crank disk geared to the table; a bar substantially parallel to the surface of the table having a pivotal connection with the disk eccentric thereto; a fulcrum spaced from the centre of the table slidably and rockably supporting the said bar; a slide movable longitudinally of and rockable on the bar; a spring dog secured to the slide, the bar being provided with grooves engageably by the dog to releasably hold the slide in an adjusted position longitudinally of the bar; a scribing point: and a clamp on the slide adapted to hold the scribing point With its axis at a permanently fixed angle to the bar, the distance beween the operative end of the point and the bar being Variable by adjusting the scribing point in the clamp.

6. A geometric scribing machine comprising a rotary table; a crank disk geared to the table; a bar substantially parallel to the surface of the table having a pivotal connection with the disk eccentric thereto; a fulcrum spaced from the centre of the table slidably and rockably supporting the said bar; a slide adjustable longitudinally of and rockable on the bar; a scribing point; a clamp on the slide adapted to hold the scribing point With its axis at a permanently fixed angle to the bar, the distance between the operative end of the point and the bar being Variable by adj usting the scribing point in the clamp; and a gauge rod slidable through the slide adapted to contact with the table, whereby a setting of the scribing point may be gauged for record.

7. A geometric scribing machine comprising a rotary table; a crank disk geared to the table; a bar substantially parallel to the surface of the table having a pivotal connection with the disk eccentric thereto; a fulcrum spaced from the centre of the table slidably and rockably supporting the said bar; a slide 

